BLUETOOTH® is a wireless communication technology for exchanging data over short distances. Bluetooth was originally conceived as an alternative to serial cables for connecting devices. Bluetooth Low Energy (BLE), which is marketed under the mark BLUETOOTH SMART®, is an extension of the Bluetooth Standard that provides considerably reduced power consumption and cost while maintaining a similar communication range. The BLE standard is incorporated into the Bluetooth Core Specification, ver. 4.0 (2010). The Bluetooth standard is maintained by the Bluetooth Special Interest Group (SIG).
Discussions are currently underway in the Bluetooth SIG for a new extension of the Bluetooth standard referred to as BLE Long Range or Bluetooth Smart Long Range. The current proposal for BLE Long Range supports two information bit rates, 125 kbps and 500 kbps. A third information rate of 250 kbs is also being considered.
In the BLE Long Range standard under consideration, data is transmitted from a transmitter to a receiver in units called data bursts. Each data burst includes a preamble that is used for time and/or frequency synchronization and a payload containing user data. The user data is transmitted at a variable data rate that varies from one data burst to another. The data rate for the user data is signaled to the receiver by inserting a rate indicator (RI) information element (IE) into the data burst. In the current proposal, the rate indicator IE requires four octets, which is a relatively large overhead for the amount of user data that is transmitted in one data burst. Therefore, more efficient ways of signaling the rate information are desired.